1. Field of the Invention
This invention relates to a process for safely decontaminating the chill water used in meat processing. The decontaminant used in the process is chlorine dioxide.
2. Description of the Prior Art
Freshly slaughtered poultry or other meat products are contaminated with pathogenic microorganisms. These microorganisms are present both on the surfaces of the animals, as well as in the intestinal tracts immediately after slaughter or evisceration. To insure product safety, recent federal regulations require microbiological testing rather than visual inspection. These regulations require that carcasses be tested for Salmonella.
A number of processes, which employ biocides for the pathogen control, have been proposed to decontaminate the chill water used to process poultry and other meat products. These processes include the use of chlorine-based sanitizers, chlorine dioxide, acidified sodium chlorite solutions, ozone and peracetic acid, but there are problems associated with using these chemicals. Ozone has poor persistence, while peracetic acid is only effective in high doses. Chlorine based sanitizers are inexpensive, but are less effective particularly at higher chill water pH. Chlorine dioxide is more effective, but can create health problems for workers exposed to it.
U.S. Pat. No. 5,389,390 suggests a process for removing bacteria from poultry, which involves using aqueous solution containing about 0.001% to about 0.2% by weight of a metal chlorite, such that the chlorite ion is in the form of chlorous acid. While this process is capable of controlling some of the microorganisms in the chill water, it does not provide flexibility with respect to adjusting the feed rate of metal chlorite to the process water being treated as the demand of the treated water increases. In addition, chlorous acid is not as effective in reducing pathogenic organisms such as salmonella and E. coli. 
U.S. Pat. No. 5,227,306 suggests a process and apparatus that provide flexibility for adjusting the feed and feed rate of chlorine dioxide to an aqueous system. The chlorine dioxide is generated on-site by an external generator, and the feed and feed rate are automatically controlled by means of a multiple feedback loop system. This process provides adequate oxidative treatment while avoiding overfeed or underfeed conditions. However, the applications described in the patent do not relate to systems where food and people are exposed to the chlorine dioxide, and does disclose the use of an air monitoring system, which would shut down the unit should vapor levels exceed defined limits.
U.S. Pat. No. 5,635,231 suggests a process for treating poultry and red meat that removes, retards, or reduces bacterial growth. The processes involve spraying the meat, either prior to or after introducing the meat into the chiller, with a solution of trialkali metal phosphate to decontaminate the meat. One of the problems with this process is that high amounts of the phosphate are used, which are discharged into the environment. U.S. Pat. No. 5,700,507 teaches that the discharge can be minimized if the trialkali metal phosphate is used in conjunction with a steam treatment.
U.S. Pat. No. 5,683,724 describes an automated process for inhibiting microbial growth in aqueous food transport or process streams. In this process, a percarboxylated acid, such as peracetic acid, is used as the microbiological control agent. The amount of percarboxylated acid fed is controlled by maintaining an ORP between 280 and 460 mV. The patent notes that the use of chlorine dioxide is undesirable, because it is a toxic gas and has an acceptable air concentration limit of 0.1 ppm. Exposure to levels above this amount may cause headaches, nausea, and respiratory problems. The patent goes on to note that expensive and intricate safety devices and/or equipment are needed when using chlorine dioxide as a decontaminant, in order to monitor the level of chlorine dioxide and maintain concentrations below 0.1 ppm. The art described in the invention addresses these concerns and provides a solution in a safe manner.
Clearly, there is a need in the meat processing industry for a process that effectively decontaminates the meat as well as the process water, which does not damage the meat being treated, and also insures the safety of workers connected with the treatment process.
All citations referred to under this description of the “Related Art” and in the “Detailed Description of the Invention” are expressly incorporated by reference.